Heterogeneous and high performance applications require a high capacity, dynamic optical network. However, it is not scalable or feasible to configure and deploy an optical network for every type of application. Optical network virtualization is a key technology for enabling the deployment of various types of applications on a single optical network infrastructure. Current approaches to virtual optical networks allocate resources in an exclusive and often excessive manner. Typically a portion of the spectrum of the virtual optical network's peak traffic is reserved along the optical paths. This leads to higher user costs and lower revenue for the carrier.
The emergence of high-performance and heterogeneous applications such as cloud computing, big data, 3D gaming, etc., has challenged the capabilities of the Internet in its current inflexible form. For example, current approaches are not sufficiently scalable or dynamic to provision a dedicated network for each network-based application. Network virtualization has been used to improve the Internet by allowing multiple virtual networks to share a common substrate physical network. In optical network virtualization, the virtual optical networks (VONs) are composed through the partitioning and/or aggregation of physical optical network resources such as transponders, regenerators, fiber links, and spectrum slices.
Optical networks are evolving from fixed-grid based approaches, where an optical path's channel width follows a rigid standard, towards a flexible-grid optical network approach, where spectrum is allocated according to capacity and/or reachability requirements. Flexible-grid optical networks greatly improve spectrum efficiency. In a flexible-grid optical network, different optical channels may have different line rates and modulation formats which require different spectrum amounts, as shown in Table I.
TABLE IRequired Spectrum AmountLine rate (Gbps)100200300400Channel width5075100125(GHz)
Complexities related to VON embedding or VON allocation play a vital role in the resource allocation of optical network virtualization. Regarding VON embedding, each VON provider (e.g., a user) requests certain resources and a physical optical network provider (e.g., the carrier) needs to allocate a part of its infrastructure resources to the VONs. Specifically, the carrier needs to map virtual nodes to physical optical nodes and map virtual links to physical optical paths. Previous approaches to VON embedding allocated resources exclusively and often excessively. For example, for a given virtual optical link, the exact spectrum amount of the link's peak traffic demand is reserved along the physical optical path. However, the spectrum utilization will be low when peak traffic demand rarely occur.
In order to increase spectrum efficiency of VONs, traditional fixed-grid optical networks are replaced by flexible-grid optical networks, where an optical channel may have flexible (e.g., variable) channel width. However, spectrum efficiency in optical network virtualization may remain undesirably low due to the fact that virtual optical networks reserve a spectrum amount based on peak traffic demands. The reserved spectrum is largely unused when peak traffic demands rarely occur.
Thus, a dynamic resource pooling and trading mechanism for optical network virtualization is needed and enables a “win-win” arrangement for carriers and their customers.